Silylium-Catalyzed Regio- and Stereoselective Carbosilylation of Ynamides with Allylic Trimethylsilanes

[Image: see text] The regio- and stereoselective carbosilylation of tosylynamides with allylic trimethylsilanes takes place under mild conditions in the presence of catalytic TMSNTf(2) or HNTf(2) to give (Z)-α-allyl-β-trimethylsilylenamides with good yields. Theoretical calculations show the activation of the C–C triple bond of the ynamides by the trimethylsilylium ion and formation of a β-trimethylsilylketenimonium cation. Further transformations of the products demonstrate the synthetic utility of this reaction.